The purpose of this project is to study the physical properties of a wide variety of biological macromolecules with the goal of correlating these properties to the structure and function of the macromolecules. The emphasis is on the thermodynamics of the interactions of these macromolecules and on their molecular size and shape. Analytical ultracentrifugation and mathematical modeling are the principal research techniques used. Studies on the association of fibrinogen with other proteins involved in blood clotting and fibrinolysis have been continued and currently deal with the association of fibrinogen with plasma and platelet Factor XIII and with the association of plasminogen with the D and E fragments of fibrinogen. Research on ricin has involved studies on a monoclonal antibody to the ricin B chain, the interaction of this antibody with ricin, and its effect on ricin toxicity both in vitro and in vivo. Research on the 27 S intermediate form of clathrin involved studies on the mechanism of formation of this form of clathrin and its relationship to the formation of clathrin baskets. Studies on synapsin have been directed toward determining the molecular weight of the monomeric form of this protein and determining whether the aggregation which it undergoes is reversible, irreversible or a combination of both. Studies on cell adhesion peptides have been directed toward determining their mode of self-association, measuring the thermodynamic parameters characterizing their self-association, measuring the thermodynamic parameters characterizing their self-association, examining their possible interactions with each other and attempting to establish a relationship between their associative behavior and their primary structure.